1. Field of the Invention
The present invention relates to a composition for forming inorganic hardened products and a process for producing hardened products from the composition. More particularly, it relates to a composition for forming inorganic hardened products which comprises a precursor of calcium aluminate trisulfate hydrate (herein TSH), at least one member selected from the group consisting of Portland cement and blast furnace slag, and gypsum, and a process for producing inorganic hardened products from the composition.
2. Description of the Prior Art
Inorganic hardened products comprising calcium aluminate trisulfate hydrate (3CaO.Al.sub.2 O.sub.3.3CaSO.sub.4.31-32H.sub.2 O) have heretofore been known as inorganic hardened products for use as building materials and the like (U.S. Pat. Nos. 3,775,143 and 3,861,929). The inorganic hardened products are produced by blending calcium aluminate monosulfate (3CaO.Al.sub.2 O.sub.3.CaSO.sub.4.12H.sub.2 O, herein referred to as "MSH") and gypsum (CaSO.sub.4.2H.sub.2 O) and optionally reinforcing fibers, adding water to the resulting blend to prepare a slurry, forming a desired shape from the slurry, and ageing and hardening the shaped article. In the process, the TSH formation reaction is as follows. ##STR1##
The thus obtained inorganic hardened products comprising TSH have a light weight, an excellent fire-resistance and an excellent workability. However, since the TSH which is the main component in the products is gradually attacked by carbon dioxide gas in air, the products have the disadvantage that their strength deteriorates with the passage of time (i.e., poor weathering resistance).